You are underestimating Dresden. He knows himself. If he thinks he will give the secret out, he will not get into the same room as Peabody. And note the second part of my plan - use the crown to learn what evidence of treachery exists. We give
that information to Dresden. It allows him to answer why he torched Peabody.
If forced to choose, forcing Red Court into a war with Fomor is a far greater strategic win than getting some (very arguably) good PR with White Council. It brings less heat to us, it damages more of our enemies, and stronger still, and it uses a unique situation in a more productive and efficient way.
We'll get good PR from our constructive contributions, i.e. weapon and equipment sales from the courts, and perhaps custom orders. We can forego a little bit of addition goodwill if we can pit two of our great enemies against each other.
You are overestimating from how away far Molly is detectable and identifiable, even in Shintai. Again. Hundreds of miles is overestimating by orders of magnitude. If it was so, Dresden would have felt our shintai activation when we were in Cleveland. Frankly, I am tired of this.
@DragonParadox could you please clarify - what is the distance (in general terms) from which Molly's power is identifiable.
At most, local spirits will feel that a foul and great power attacked the plane amidst a conjured storm.
I believe that you are overestimating divination in this case. Postcognition (viewing the past) was never shown as something easily done or commonly available. Way too many plots would have been resolved if it was, even for movers and shakers of the world.
EDIT: And remember, we don't the deception to hold forever. Only long enough that Red Court retaliates against fomori. It doesn't matter if they learn the truth after that.